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At least 937 records · Page 52Linked to original sources
PubMed1987

Effect of cold-temperature exposure and acclimation on amino acid pool changes and enzyme activities of rat brown adipose tissue.

The amino acid pool composition and its concentration ratios with respect to blood and plasma, as well as the activities of alanine, aspartate and branched chain amino acid transaminases, glutamine synthetase, adenylate deaminase and glutamate dehydrogenase have been studied in the interscapular brown adipose tissue of control, 12-h cold-exposed and 15-day cold-acclimated rats. Cold temperature affected the amino acid metabolism and pool composition more intensely after 15 days than after 12-h cold-exposure, even though the patterns of change were very similar in both groups. Cold temperatures induced a decrease in glutamine and an increase in glutamate concentration in the tissue. This probably increased the metabolism of branched chain amino acids and caused a decrease in adenylate deaminase activity. It also seemed to increase alanine utilization. We concluded that amino acid metabolism in brown adipose tissue is enhanced by cold temperature acclimation.

AMP Deaminase↗
PubMed1983

Ketone bodies in cold-acclimated rats.

Acclimation temperature (28 or 5 degrees C) modifies acetoacetate (AA) and beta-hydroxybutyrate (BOH) levels in blood and liver. In the fed state AA and BOH levels were increased in blood and liver of 5 degrees C adapted rats. In the fasting state (24 or 48 hr) an antiketotic action of cold acclimation was observed. It was found to be more pronounced with high fat diet. These effects were more marked in the blood than in the liver. The variations in ketonemia are discussed with relation to the role of liver in cold adapted rats.

3-Hydroxybutyric Acid↗
PubMed1985

Viability control and oxygen consumption of isolated hepatocytes from thermally acclimated rainbow trout (Salmo gairdnerii).

Hepatocytes were isolated by collagenase perfusion of the liver from rainbow trout acclimated to 10 and 20 degrees C. The suitability of the stimulation of cellular respiration by succinate as criterion of viability was examined and discussed. Endogenous respiration rates of the hepatocytes were a function of cell size to the power of 0.8. Specific oxygen consumption of the hepatocytes and respiratory control ratios of the mitochondria in situ were independent of acclimation temperature.

Acclimatization↗
PubMed1992

Biosynthesis of NAD-sorbitol dehydrogenase is induced by acclimation at 5 degrees C in diapause eggs of the silkworm, Bombyx mori.

1. In diapausing eggs of the silkworm, Bombyx mori, activity of NAD-sorbitol dehydrogenase (EC 1.1.1.14, SDH) is almost negligible, but is increased by acclimation at 5 degrees C (Yaginuma et al., 1990, J. comp. Physiol. B160, 277-285). To elucidate the mechanism regulating SDH activity, the following experiments were conducted. Anti-SDH serum was made in a mouse using purified sheep liver SDH. 2. This antiserum reacted with Bombyx egg SDH purified partially by Blue Sepharose CL-6B and Sephacryl S-300 column chromatographies. 3. SDS-PAGE and immunoblotting analyses using the antiserum showed that SDH activity was correlated with the amount of the enzyme protein. 4. These results indicate that biosynthesis of SDH is induced by acclimation at 5 degrees C in diapause eggs of B. mori.

Acclimatization↗
PubMed1983

Long scotophase acclimation increases free urinary catecholamine content in the rat.

1. Acclimation of laboratory rats Rattus norvegicus albino to long scotophase 8L:16D and 4L:20D at an ambient temperature (Ta) of 25 degrees C caused an increase in urinary free catecholamine compared to 12L:12D at Ta = 25 degrees C. 2. Transferring the same individuals from 8L:16D to 12L:12D (at Ta = 25 degrees C) caused a decrease in this factor. 3. The results of this study suggest that acclimation to long scotophase increases sympathetic nervous system and chromaffine cell activities.

Animals↗
PubMed1986

Central metabolism of beta-endorphin in different species of temperature acclimated rodents.

The purpose of this study was to characterize the central metabolism/processing of beta-endorphin in wild, desert rodents and to study the effect of heat and cold acclimation on central metabolism/processing and beta-endorphin half-life. This report suggests that a shift occurs in the processing of beta-endorphin in desert rodents acclimated to heat and cold leading to an accumulation of gamma-type endorphins. The data support a significant difference in beta-endorphin half-life between the rodents and the laboratory white rat.

Acclimatization↗
PubMed2005

Differential protein expression profiles in anterior gills of Eriocheir sinensis during acclimation to cadmium.

Using a proteomic approach, we characterized different protein expression profiles in anterior gills of the Chinese mitten crab, Eriocheir sinensis, after cadmium (Cd) exposure. Two experimental conditions were tested: (i) an acute exposure (i.e. 500 microg Cd l(-1) for 3 days) for which physiological, biochemical and ultrastructural damage have been observed previously; (ii) a chronic exposure (i.e. 50 microg Cd l(-1) for 30 days) resulting in physiological acclimation, i.e. increased resistance to a subsequent acute exposure. Two-dimensional gel electrophoresis (2-DE) revealed six protein spots differentially expressed after acute, and 31 after chronic Cd exposure. From these spots, 15 protein species were identified using MS/MS micro-sequencing and MS BLAST database searches. Alpha tubulin, glutathione S-transferase and crustacean calcium-binding protein 23 were down-regulated after an acute exposure, whereas another glutathione S-transferase isoform was up-regulated. Furthermore, analyses revealed the over-expression of protein disulfide isomerase, thioredoxin peroxidase, glutathione S-transferase, a proteasome subunit and cathepsin D after chronic exposure. Under the same condition, ATP synthase beta, alpha tubulin, arginine kinase, glyceraldehyde-3-phosphate dehydrogenase and malate dehydrogenase were down-regulated. These results demonstrate that acute and chronic exposure to waterborne Cd induced different responses at the protein expression level. Protein identification supports the idea that Cd mainly exerts its toxicity through oxidative stress induction and sulfhydryl-group binding. As a result, analyses showed the up-regulation of several antioxidant enzymes and chaperonins during acclimation process. The gill proteolytic capacity seems also to be increased. On the other hand, the clearly decreased abundance of several enzymes involved in energy transfer suggests that chronic metal exposure induced an important metabolic reshuffling.

Acclimatization↗
PubMed2005

A cell-based model for the photoacclimation and CO(2)-acclimation of the photosynthetic apparatus.

We have developed a mathematical model based on the underlying mechanisms concerning the responses of the photosynthetic apparatus of a microalga cell which grows under constant incident light intensity and ambient CO(2) concentration. Photosynthesis involves light and carbon-fixation reactions which are mutually dependent and affect each other, but existing models for photosynthesis don't account for both reactions at once. Our modeling approach allows us to derive distinct equations for the rates of oxygen production, NADPH production, carbon dioxide fixation, carbohydrate production, and rejected energy, which are generally different. The production rates of the photosynthesis products are hyperbolic functions of light and CO(2) concentration. The model predicts that in the absence of photoinhibition, CO(2)-inhibition, photorespiration, and chlororespiration, a cell acclimated to high light and/or CO(2) concentration has higher photosynthetic capacity and lower photosynthetic efficiency than does a cell acclimated to low conditions. This results in crossing between the two curves which represent the oxygen production rates and carbon fixation rates in low and high conditions. Finally, in the absence of photoinhibition and CO(2)-inhibition, the model predicts the carbohydrate production rate in terms of both light intensity and CO(2) concentration.

Adaptation, Physiological↗
PubMed2005

Electrocardiogram and heart rate in response to temperature acclimation in three representative vertebrates.

Comparisons of electrocardiogram (ECG) and heart rate characteristics of three representative species in response to temperature acclimation were studied. In toad (Bufo raddei), T wave had positive, negative and flat patterns, which was different from positive in lizard (Eremias multiocellata), blunt and broad in bird (Alectories magna). The duration of P-R interval, Q-T interval and QRS complex interval reduced with increasing temperature in toad, but the P-R and T-P intervals were affected mostly, the QRS and R-T intervals were relatively less affected in lizard. In the bird, the voltage of P, S and T wave scarcely changed, R wave increased slightly with temperature going up in the thermal neutral zone (20-35 degrees C), T and S waves tended to increase and P-S and S-T intervals shortened when temperature went below the neutral zone. Heart rate was high and relatively steady in bird, but changed linearly in relation to temperature in toad and lizard. The increasing of heart rate with temperature was mainly caused by the T-P interval shortened in lizard, but P-S and S-T intervals shortened in bird. Comparisons of ECG and heart rate characteristics of three representative species in response to temperature acclimation reflected phylogenetically based constraints on pacemaker rates, oxygen supply and modulatory mechanisms.

Acclimatization↗
PubMed2006

Gill Na(+), K(+)-ATPase in a series of hyper-regulating gammarid amphipods: enzyme characterisation and the effects of salinity acclimation.

The enzyme Na(+), K(+)-ATPase was investigated in the gills of selected hyper-regulating gammarid amphipods. Gill Na(+), K(+)-ATPase was characterised with respect to the main cation and co-factor concentrations for the freshwater amphipod Gammarus pulex. The optimum cation and co-factor concentrations for maximal gill Na(+), K(+)-ATPase activity in G. pulex were 100mM Na(+), 15mM K(+), 15mM Mg(2+) and 5mM ATP, at pH 7.2. The effects of salinity acclimation on gill Na(+), K(+)-ATPase activity and haemolymph sodium concentrations was investigated in selected gammarid amphipods from different salinity environments. Maximal enzyme activity occurred in all gammarids when acclimated to the most dilute media. This maximal activity coincided with the largest sodium gradient between the haemolymph and the external media. As the haemolymph/medium sodium gradient decreased, a concomitant reduction in gill Na(+), K(+)-ATPase activity occurred. This implicates the involvement of gill Na(+), K(+)-ATPase in the active uptake of sodium from dilute media in hyper-regulating gammarids.

Acclimatization↗
PubMed2006

Effects of acclimation and incubation temperature on the glutathione antioxidant system in killifish and RTH-149 cells.

Glutathione (GSH) is an important antioxidant that is involved in a multitude of cellular processes. However, in fish, GSH levels, turnover, and activity of associated enzymes are low when compared to those of mammals. To determine whether temperature influences the GSH antioxidant system in fish, and can explain the differences in GSH between fish and mammals, we examined the effects of acclimation temperature on total GSH (tGSH) levels and apparent half-life (as an estimate of turnover) in a rainbow trout hepatoma cell line (RTH-149), and GSH levels, and glutathione peroxidase (GPx) and reductase (GR) activity in the eurythermal killifish. Increasing incubation temperature decreased half-life and transiently increased levels of tGSH in RTH-149 cells. In killifish, increased acclimation temperature increased tGSH levels in the liver, brain and muscle, and increased hepatic GPx and GR activities. When the relationships between temperature and GSH half-life, levels and enzyme activity were extrapolated to 37 degrees C, temperature could only partially accounted for differences in the GSH antioxidant system in fish compared to mammals. The differences in the GSH antioxidant system between fish and mammals may not be solely due to temperature effects, but also to the increased metabolic cost of endothermy in mammals.

Acclimatization↗
PubMed2006

Antifreeze glycoprotein levels in Antarctic notothenioid fishes inhabiting different thermal environments and the effect of warm acclimation.

A quantification method was developed to determine the concentrations of the major antifreeze glycoprotein (AFGP) isoforms in the blood of Antarctic notothenioid fishes. Serum samples were precipitated with 2.5% TCA and the supernatant containing AFGPs were chromatographed on an HPLC size exclusion column and the concentrations of the major AFGP size classes were determined from the areas of the corresponding peaks in the elution profile. Eight species of Antarctic notothenioid fishes were examined and their blood AFGP concentrations varied from 5 to 35 mg/mL. All of these fishes synthesized both the large and small AFGPs, but maintained higher levels of small AFGPs than the large ones in their blood. The species inhabiting more severe water environments (lower temperature and presence of ice) had higher serum AFGP levels than those in milder environments. The cryopelagic Pagothenia borchgrevinki decreased their blood AFGP concentrations in response to warm acclimation, but to a much lower extent in comparison to the antifreeze-bearing fishes in the Northern Hemisphere. After being warm acclimated at +4 degrees C for 16 weeks, the serum concentrations of the small and large AFGPs were decreased by about 60% and 20%, respectively.

Acclimatization↗
PubMed2006

Stress protein response in two sibling species of Marenzelleria (Polychaeta: Spionidae): is there an influence of acclimation salinity?

The induction and synthesis of stress proteins in the polychaete sibling species Marenzelleria viridis and M. neglecta was investigated at two different acclimation salinities (10 and 25 ppt). By in vitro labeling of dissected metameres with (35)S-methionine/cysteine and electrophoretic separation, four size classes of heat shock proteins (Hsps) were detected corresponding to 86, 78, 75 and 27 kDa. All Hsps, with the exception of Hsp86, represent a complex of multiple isoforms. The sibling species differed in three aspects of their heat shock response: (1) the induction temperature for Hsp75 synthesis was 25 degrees C and 30 degrees C in M. viridis and M. neglecta, respectively; (2) the relative level of synthesis of Hsp75 was higher in M. viridis; (3) the heat shock response was inactivated at a higher temperature in M. neglecta compared to M. viridis. The results showed that acclimation salinity had no explicit effect on Hsp synthesis in either species and that M. viridis was thermally more sensitive than its sibling species. We proposed that temperature, alone or in combination with other abiotic factors, plays a far greater role in the biogeographic distribution in Marenzelleria spp. than has been estimated so far.

Acclimatization↗
PubMed2005

Hyper-osmoregulatory capacity of the Chinese mitten crab (Eriocheir sinensis) exposed to cadmium; acclimation during chronic exposure.

The aim of this study was to evaluate the effects of waterborne cadmium on hyper-osmoregulatory capacity of the Chinese mitten crab Eriocheir sinensis acclimated to freshwater. For this purpose, crabs were submitted to acute (0.5 mg Cd L(-1) for 1, 2 or 3 days), chronic (10 or 50 microg Cd L(-1) for 30 days) or chronic, immediately followed by acute, exposure. While no effect was observed after 1 or 2 days, hemolymph osmolality, Na(+) and Cl(-) concentrations were significantly reduced after 3 days of acute exposure. Under this latter condition, the respiratory anterior gill ultrastructure, Na(+)/K(+)-ATPase and cytochrome c oxidase activities were significantly impaired. In contrast, the osmoregulatory posterior gill was unaffected for all treatments. As a consequence, we suggest that the observed hyper-osmoregulatory capacity impairment is the result of increased dissipative flow of ions and/or water through anterior gills. In contrast to acute exposure, chronic exposure did not induce any observable effect. However, crabs submitted to a known deleterious acute condition (0.5 mg Cd L(-1) for 3 days) directly after chronic exposure to 50 microg Cd L(-1) for 30 days showed normal hyper-osmoregulatory capacity with no change in gill Na(+)/K(+)-ATPase activity, and only little disturbance of anterior gill ultrastructure. These results demonstrate that a chronic cadmium exposure can induce acclimation mechanisms related to osmoregulation in this euryhaline decapod crustacean.

Acclimatization↗
PubMed2005

Carbohydrate partitioning between upper and lower regions of the crown in oat and rye during cold acclimation and freezing.

Carbohydrates have long been recognized as an important aspect of freezing tolerance in plants but the association between these two factors is often ambiguous. To help clarify the relationship, the allocation of carbohydrates between specific tissues within the over wintering organ (crown) of winter cereals was measured. A winter-hardy and non-winter-hardy oat (Avena sativa L.), and a rye (Secale cereale L.) cultivar were grown and frozen under controlled conditions. Crown tissue was fractionated into an upper portion, called the apical region, and a lower portion, called the lower crown. These tissues were ground in liquid N and extracted with water. Extracts were analyzed by HPLC for the simple sugars, sucrose, glucose, fructose, and for fructan of various size classes. After 3 weeks of cold acclimation at 3 degrees C, carbohydrates accounted for approximately 40% of the dry weight of oats and 60% of the dry weight of rye. The apical region, which is the tissue within the crown that acclimates to the greatest extent, was generally 10% higher in total carbohydrates than the lower crown. During a mild freeze, various carbohydrates were allocated differently between specific tissues in the three genotypes. When frozen, fructan generally decreased to a greater extent in the lower crown than in the apical region but sugars increased more in the apical region than in the lower crown. Results suggest that to understand how carbohydrates relate to freezing tolerance, regions of the crown that endure freezing stress differently should be compared.

Acclimatization↗
PubMed2006

Cold acclimation of the Arabidopsis dgd1 mutant results in recovery from photosystem I-limited photosynthesis.

We compared the thylakoid membrane composition and photosynthetic properties of non- and cold-acclimated leaves from the dgd1 mutant (lacking >90% of digalactosyl-diacylglycerol; DGDG) and wild type (WT) Arabidopsis thaliana. In contrast to warm grown plants, cold-acclimated dgd1 leaves recovered pigment-protein pools and photosynthetic function equivalent to WT. Surprisingly, this recovery was not correlated with an increase in DGDG. When returned to warm temperatures the severe dgd1 mutant phenotype reappeared. We conclude that the relative recovery of photosynthetic activity at 5 degrees C resulted from a temperature/lipid interaction enabling the stable assembly of PSI complexes in the thylakoid.

Acclimatization↗
PubMed2006

Biodegradation kinetics of 2,4-dichlorophenol by acclimated mixed cultures.

The biodegradation kinetics of 2,4-dichlorophenol (2,4-DCP) by culture (Culture M) acclimated to mixture of 4-chlorophenol (4-CP) and 2,4-DCP and the culture (Culture 4) acclimated to 4-CP only were investigated in aerobic batch reactors. Also, pure strains isolated from mixed cultures were searched for their ability towards the biodegradation of 2,4-DCP. Culture 4 was able to completely degrade 2,4-DCP up to 80 mg/L within 30 h and removal efficiency dropped to 21% upon increasing initial concentration to 108.8 mg/L. When the Culture M was used, complete degradation of 2,4-DCP in the range of 12.5-104.4 mg/L was attained. A linear relationship between time required for complete degradation and initial 2,4-DCP concentrations was observed for both mixed cultures. It was observed that the Haldane equation can be used to predict specific degradation rate (SDR) (R(2)>0.99) as a function of initial 2,4-DCP concentrations and it adequately describes 2,4-DCP concentration profiles. Both of the mixed cultures settled well, which is important to maintain good removal efficiency for longer periods of time for real full-scale applications. Although the pure strains isolated from mixed cultures were found to have higher SDR of 2,4-DCP compared to mixed cultures, they did not settle well under quiescent conditions.

Bacteria↗